package com.soda.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ImgServlet extends HttpServlet {

	private Color getRandColor(int fc, int bc) { // 给定范围获得随机颜色;
		Random random = new Random();
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		// System.out.println("r = " + r + ", g = " + g + ", b = " + b);
		return new Color(r, g, b);
	}
	
	public void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {

		resp.setContentType("image/jpeg");

		resp.addHeader("pragma", "NO-cache");

		resp.addHeader("Cache-Control", "no-cache");

		resp.addDateHeader("Expries", 0);

		// 在内存中创建图象
		int width = 90, height = 35;
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);

		// 获取图形上下文
		Graphics g = image.getGraphics();

		// 生成随机类
		Random random = new Random();

		// 设定背景色
		g.setColor(getRandColor(200, 255));
		g.fillRect(0, 0, width, height);

		// 设定字体
		g.setFont(new Font("隶书", Font.PLAIN, 35));

		// 画边框
		g.drawRect(0, 0, width - 1, height - 1);

		// 随机产生20条干扰线，使图象中的认证码不易被其它程序探测到

		for (int i = 0; i < 25; i++) {
			g.setColor(getRandColor(80, 140));
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(400) - 200;
			int yl = random.nextInt(400) - 200;
			g.drawLine(x, y, x + xl, y + yl);
		}

		// 取随机产生的认证码(4位数字)
		String sRand = "";
		for (int i = 0; i < 4; i++) {
			String rand = "" + (char) (random.nextInt(26) + 97);
			sRand += rand;
			// 将认证码显示到图象中
			g.setColor(new Color(15 + random.nextInt(110), 15 + random
					.nextInt(110), 15 + random.nextInt(110)));
			// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
			g.drawString(rand, 15 * i + 2, 30);
		}
		// 将认证码存入SESSION
		// req.setAttribute("code", sRand);
		req.getSession().setAttribute("code", sRand);
		// 图象生效
		g.dispose();

		// 输出图象到页面
		ImageIO.write(image, "JPEG", resp.getOutputStream());
	

	}


	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	doGet(request, response);
	}

}
